The present invention relates to a process for the heat treatment of fine-grained iron ore and for the conversion of the heat-treated iron ore to metallic iron. According to the invention the term "metallic iron" is understood to be metallic iron in the form of sponge iron and Fe.sub.3 C, in which the iron is present in the valence state 0, and mixtures of metallic iron and Fe.sub.3 C.
The direct reduction of iron ore has proved very effective in a fluidized bed. A particularly effective process is known from EP-PS 0 255 180. In the direct use of fine ores having a grain size &lt;50 .mu.m, unsatisfactory results are obtained upon direct reduction in the fluidized bed. What is disadvantageous therein is firstly incomplete separation in the hot cyclone and secondly that upon the final-reduction the fluidizing rate has to be reduced to such an extent that very large reactors have to be used, which is uneconomic.
The object of the present invention is to provide an economic and environmentally sound process for the heat treatment of fine-grained iron ore which cannot be converted directly to metallic iron. A further object of the present invention is to provide a process for the production of metallic iron from the heat-treated, fine-grained iron ore.